1. Field of the Invention
The present invention relates to a system for transporting an unprocessed well stream comprising a multiphase, multicomponent mixture over a long distance from one or several wells to a terminal.
2. Related Art
Known field development concepts require that unprocessed well streams not be transported long distances from the wellheads. For underwater wellhead locations the distance, for instance between a well head and a processing plant, will be limited to a maximum of 10-15 km. The primary reason for this is that the reservoir pressure alone is not able to provide satisfying pressure levels for an economically justifiable long distance transport, as the pressure lost will lead to a lower field utilization. In deep water the positioning of fixed or floating processing plants close to the production wells will lead to considerable extra expense compared with placing plants onshore or in shallower water.
Another problem is the low operational flexibility of long distance pipelines, due to the fact that each pipeline is adapted to a fluid with particular phase characteristics. This requires considerable pretreatment of the well streams before the well streams can be introduced into long distance transport pipelines. This leads to considerable disadvantages when the field units are geographically separated by large distances. Another problem is that the well stream properties within the same field may vary, and also that considerable variation in the stream from each well may vary throughout the production period.
A third problem is related to the fact that transport pipelines of different types, for instance pressure classes, cannot be joined to each other without expensive additional installations offshore.